It has been found that intradermal delivery of certain substances and vaccines is more effective than when it is delivered intramuscularly. While traditional jet injectors are known for injecting a substance intradermally, they are not capable of properly providing an intradermal injection.
Jet injectors utilize the stream of the injected substance to overcome the resistance of the skin to penetration. This high velocity stream of substance then also constitutes the substance to be delivered. Traditional jet injectors require high energy to penetrate the top layers of the skin which provide most of the resistance. Providing sufficient power for such penetration and then depositing the material to be injected just under the surface skin layer, such as what is required for an intradermal injection is challenging. An injection weak enough to administer the material intradermally may be so weak that not all the substance is delivered as the skin surface is not completely penetrated by the jet. An injection may be to sufficient to deliver the entire substance but so strong that most of the injected substance is delivered much deeper than the superficial layers of the skin.
Traditional needle injection methods aimed at delivering a substance intradermally also suffer from major shortcomings. They require a lot of skill on the part of the person delivering the injection as careful placement of the needle as part of the insertion process is required. Injecting the substance to fast from a traditional device by pushing on substance being pushed back out of the injection hole once the needle is removed. The patient is not comfortable during what seems like a long injection due to the desire to deliver the injected substance slowly to prevent the substance from coming back out of the injection site. Thus improvements in intradermal injectors are needed.